Question

1.How are the various meters connected in a circuit : series or parrellel.

2. which color probes, when properly inserted, go into which holes of a multimeter in the ohm and voltage measuring mode. And, given a positive voltage measurment, in this properly set meter, which way will the current flow?

3. Determine maximum permitted voltage or current for a rated resistor.

4. slide wire potentiometer : electric field in the wire and how to calculate potential difference alone the wire.

5. what is the output effect of a pn junction diode on an input ac voltage. 6. given an electric potential versus position plot, be able to identify. a.elecric field directions b. equalibrium positions c. electric field stregths: maxima and minima d. potential energy maxima and minima 7. write the nodal current equations and voltage loop equations for a multiple loop circuit.

Answer 1

1.How are the various meters connected in a circuit : series or parallel.

Ans: Voltmeter: Should be connected in parallel with circuit element as it will measure voltage across the element.

         Ammeter: Should be connected in series with circuit as it will measure current through the element.

         Ohmmeter: Should be connected across the element and the element should be isolated from the main circuit for      accurate readings.

2. Which color probes, when properly inserted, go into which holes of a multimeter in the ohm and voltage measuring mode. And, given a positive voltage measurement, in this properly set meter, which way will the current flow?

Ans: There are different ports in a multimeter. The Most basic ports available in a typical multimeter are COM Port, V Port, 10A Port. The multimeter comes with two different color probe, one is red and another one is black.

Always Black color probe should be connected to COM port. When we need to measure voltage or resistance or continuity then we need to connect the red probe to V port. When we need to measure current (below 10 amps) , then we need to connect the red probe to 10A port.

When we measure the voltage of a circuit, then we connect the multimeter in parallel with the circuit and multimeter offers a very high impedance to the circuit so that very small amount of current goes into multimeter. The negligible amount of current flows from red probe through multimeter to black probe.

Note: Always red probe should be connected to the positive side of the circuit or element and black probe to the other side.

3. Determine maximum permitted voltage or current for a rated resistor.

Ans: A typical resistor is always rated in ohm and watt i.e 10 , 1/4 watt or 150 , 1 watt or 2 , 1/2 watt.

Let's assume, we have "X" ohm "Y" watt resistor with us.

As we know,

Power(P) = VI = V² / R = I² R ( Where V = Voltage in volts, I = Current in amps, R= Resistance in ohm and Power in watts)

To determine maximum permitted voltage,

P = V² / R

Or, Y = V² / X

Or, V = (X*Y)^1/2

So maximum permitted voltage is (X*Y)^1/2 Volts.

To determine maximum permitted current,

P = I² R

Or, Y = I² X

Or, I = (Y/X)^1/2

So maximum permitted current is (Y/X)^1/2 Amps.

4. Slide wire potentiometer : electric field in the wire and how to calculate potential difference along the wire.

Ans: Let the length of the wire is L , cross section of the wire is A, and the resistivity of the wire is , Current through the wire is I.

So the potential difference along the wire is,

V = I*R

Or, V = I * * L/A                            ( As we know R = * L/A)

Or, V = IL/A

So the potential difference along the wire is IL/A.

To find out Potential gradient(K) of the wire in volts/meter,

K= V/L

Or, K = (I * * L/A) / L

Or, K = I * /A

So the potential gradient of the wire is I / A

I hope this will help you, Thank You.